Benzosulfones as photochemically activated sulfur dioxide (SO₂) donors

Abstract

Sulfur dioxide (SO2) is a gaseous environmental pollutant which is routinely used in industry as a preservative and antimicrobial. Recent data suggests that SO2 may have value as a therapeutic agent. However, due to its gaseous nature, localizing SO2 generation is challenging. Herein, various 1,3-dihydrobenzo[c]thiophene 2,2-dioxides (benzosulfones) were prepared as candidates for photochemically activated sulfur dioxide (SO2) generation. These compounds were found to be stable in buffer but were photolysed upon irradiation with UV light to generate SO2. Our data indicates that photolysis of benzosulfones depends on substituents, and that the presence of electron donating groups results in an enhanced yield of SO2.

Sulfur dioxide prodrugs: triggered release of SO2via a click reaction

“…Chakrapani and colleagues have reported clever designs that utilize biological thiol (cysteine) and UV light to trigger the release of SO 2 gas from donors. 16, 17 They also developed elegant work on using benzosultines to generate SO 2 under physiological conditions. 18 Recently, Xian’s group reported benzothiazole sulfinate (BTS) as a pH dependent water soluble SO 2 donor.…”

SO2 Donors and Prodrugs, and Their Possible Applications: A Review

“…1-Phenyl-benzosulfone was found to be a more stable form of 1-phenyl-benzosultine ( 6 ) (Malwal et al, 2013 ). To develop UV light-triggered SO 2 prodrugs, Chakrapani's group further exploited the stability of benzosulfones (Malwal and Chakrapani, 2015 ). Three classes of benzosulfone were designed with varied substitution groups on the 1-position and the aryl ring ( 8 , Scheme 3 ).…”

The Sulfolene Protecting Group: Observation of a Direct Photoinitiated Cheletropic Ring Opening

“…SO 2 photoexpulsion from sulfolene has previously been observed, but is limited to triplet‐sensitized expulsions, [18] or to stepwise reactions forming stable biradical species which decay on to form products [19] . Studies of the triplet sensitized reaction initially indicated that the triplet state deactivates via intersystem crossing (ISC) to a vibrationally excited electronic ground‐state from which expulsion would occur.…”